Despite low numbers of actual reported cases of AIDS in adolescents, human immunodeficiency virus (HIV) appears to be spreading in individuals in this age group, particularly among minority adolescents from urban areas where the overall rate of HIV infection in the community is high. We seek to demonstrate that this increased rate among African-American and Hispanic adolescents is primarily related to contact with drugs, with others who use drugs, or with the "drug culture." Our specific aims include the following: 1) To establish that HIV infection in urban adolescents is associated with drug use or contact with drug users; 2) To show that other HIV risk behaviors are associated with drug use or contact with drug users; 3) To show that other sexually transmitted diseases are much less likely to be associated with drug use; 4) To establish the fact that female adolescents have a greater risk of HIV infection if they use drugs or are the sex partners of drug users while the rate among their male counterparts is highest for those who have had sex with other men; 5) To establish that the prevalence of HIV infection in our patient population is the same in female adolescents as it is in male adolescents; 6) To show that the probability of current drug use can be measured by a self-report questionnaire instrument. Once these associations are established, we hope the data will serve as the catalyst for revising the AIDS prevention programs in this jurisdiction as well as in other urban areas so that drug education can assume an increasing role in the AIDS prevention effort. We will accomplish these aims and this overall program objective by conducting a four year, serial, observational study of HIV seroprevalence, drug use, risk behaviors and historical health information in adolescents seen for health care in the ambulatory health services of a large urban pediatric hospital. A unique system for linking information while removing personal identifiers will allow us to conduct this study in a blinded, unlinked, and anonymous fashion. This will eliminate selection bias and problems with volunteer samples, while providing an accurate assessment HIV infection and its antecedent risk factors in our patients.